Core materials



Patented May 9, 1950 CORE MATERIALS Jim E. Allison, Elmhurst, 1u.,assignor to The Quaker Oats Company, Chicago, 111., a corporation of NewJersey No Drawing. Application June 21, 1946, Serial No. 678,352

2 Claims. 1

The present invention relates to core materials, and more particularlyto cereal core binders employed in their production.

My invention is concerned with the production of a corn product corebinder. In the past various corn products have been proposed by theprior art as foundry core binders. For example, a first type of priorart product is produced by sending a heavy slurry of mill starch from acorn wet processing plant over the hot surfaces of internally. heatedrolls. The contact of the mill starch slurry with the heated surfacescauses the gelatinization of the starch and the formation of a flakedproduct which is then ground to a fine powder. A second type of priorart product is made by moistening degerminated corn and subjecting themoistened product to a heated roll surface whereby the starch in thedegerminated ground corn is gelatinized and whereby the whole product isflaked. The flaked gelatinized product is then ground to a fine powder.

I have found that ground degerminated corn can, when properly processed,be made into an emcient core binder having qualities superior to thatobtained with corn product fractions of the prior art. Heretofore inmaking foundry cores for use in the production of castings, it has beenthe practice to mix core sand with a variety of dry or liquid binders,namely: various corn product fractions, pulverized cereals, pulverizedfoundry pitch, rosin or casein, sulphite pulp waste liquor, molasses, orvarious oils such as linseed, soybean or other vegetable oils. Themixture of sand and binder is then moistened with sumcient water so thatit can be inserted into core boxes of various shapes and sizes corresponding to the shape and sizes of cavities it is desired to produce bymeans of the cores.

When the corebox is removed, the grains of sand must be bound togetherby the binder so as to permit handling in an approved manner andtransferring to an oven. In the oven the cores are baked to expel thewater, drive off volatile eonstituents and give a core capable ofwithstanding the pressure encountered in casting operations. In casting,the heat of the molten.

metal burns out the binder, the gases from which. vent through the coreand molds, leaving the core My corn flour produces cores or moldspossessing much greater strength than cores or molds employing cerealbinders which have been processed according to the methods described inthe prior art.

Accordingly one of the objects of my invention is the treatment of aground degerminated corn product by a simple and inexpensive methodwhereby it will be adapted for use as a core binder.

A further object is to produce an improved high tensile strength sandcore material such as is used in the casting of metals.

Another object of my invention is the production of a grounddegerminated corn core binder having qualities superior to that of othercorn product core binders.

Still another object is the development of a process which makespossible the use of a corn milling product which in normal times is adrug on the market. During the dry milling of degerminated corn acertain percentage of a more or less finely ground product is obtained,which according to its degree of fineness, is known as corn flour orcorn cream meal. That portion which passes through a mesh screen isclassified as a corn hour and the product which passes through a 46 meshscreen and is retained on a 95 mesh screen is commonly known as corncream meal although sometimes broader ranges of particle size may beincluded under that terminology. My process enables the production of avaluable and efiicient high quality core binder from corn cream meal.

In practicing my invention, I have found that com cream meal containing10 to 15% moisture can be readily and economically pelleted. Anysuitable means of pelleting may be employed, but I prefer to extrude thematerial through a die fitted with a revolving knife which is so adjusted that it cuts the pellets to an appropriate length. For ease ofhandling, I prefer pellets 5%" in diameter and in length. While the useof steam is not necessary in the extrusion process. it is preferredsince it apparently lubricates the dies, thus making for more emcientoperation.

A charge of pellets produced as above described is placed in a puflinggun. This gun may be any of the conventional types of equipment used forthe pulling of cereals such as rice, oats, wheat, corn, etc. Examplesare the Anderson pulling gun such as that described in U. S.= Patent1,725,171 and the Plews pufling gun described in U. S. Patent 2,116,212.superheated steam is allowed to enter the gun chamber at a temperatureof 620 F. The steam passes through the pellets and expels any airpresent in the chamber. The cover of the pufllng gun or chamber is thenclosed and the internal pressure allowed to build up to 175 lbs. persquare inch. The chamber is maintained at this pressure for about threeminutes whereupon the pressure is suddenly released. The resultingpuffed corn cream meal cereal is then conveyed to a rotary drier anddried to a moisture content of about 8%. The dried material is thenground or pulverized to a flour of about 60 mesh. In the puihng processthe temperature should'be above the gelatinizing temperature of thestarch in the cereal. A workable range is obtained by using superheatedsteam within a temperature range.of 375 to 800 F. and a pressure rangeof 75 to 200 lbs. per square inch.

Cores manufactured from the above puffed pulverized corn cream meal arecharacterized by greater strength as indicated particularly by drycompression, air set compression and dry tensile strength tests. Thefollowing tests show the core binding qualities obtained with the pufiedand then ground corn cream meal of the present invention as comparedwith flaked and pulverized corn products of the prior art.

A mixture of one part of pufied corn cream meal,- 50 parts of sand and1.5 parts of water was mixed for 8 minutes and produced a core which,when allowed to set in air for 30 minutes at room temperature, gave anair set compression of 16.8 lbs. per square inch and when baked for twohours at 400 F. gave a dry compression of 244 lbs. per square inch. When30 parts of sand and 1 part of linseed oil were added to the aboveingredients and another core formed and baked for one hour at 400 F.,the resulting core had a tensile strength of 224 lbs. per square inch.

When a flaked and powdered mill starch product (unpufled) was subjectedto the same series of tests the air set compression was 8.8, the drycompression 100 and the dry tensile strength 140 lbs. per square inch.It is thus seen that the pulled corn cream meal product had a drycompression strength or twice that or the unpuiled product and an airset compression and dry tensile strength of somewhat less than doublethan that of the unpuil'ed product.

when a flaked and powdered product prepared from degerminated corn grits(unpufled) was subjected to similar sets of tests under identicalconditions the dry compression. air set compression, and dry tensilestrengh was 115, 12.6 and 181 lbs. per square inch, respectively. Here,too, the puffed corn cream meal product is distinctly superior.

It is apparent from the above data that the pufied corn cream meal corebinder is superior to both of the other com product binders. In place ofpuii'ed corn cream meal one could use pulled corn flour and obtainsimilar advantageous results.

While I have in the above description disclosed what I believe to be apreferred and practical embodiment of my invention it will be understoodthat the specific details, including the technique by which the processis carried out, are by way of example and not to be construed aslimiting the scope of theinvention.

I claim:

1. A casting core material comprising a mix ture of sand, a drying oil,and degerminated, pelleted, puffed and pulverized corn flour.

2. A casting core material comprising a mixture of sand, a drying oil,and pulverized corn product formed by pelleting, steam pufllng andcomminuting a degerminated, comminuted corn product.

JIM E. ALLISON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 707,892 Anderson Aug. 26, 1902921,030 Wagner et a1 May 11, 1909 1,429,879 Hill Sept. 19, 19222,181,372 Kellogg Nov. 28, 1939 2,206,369 Salzberg July 2, 19402,289,030 Miller July 7, 1942 2,388,904 Collatz Nov. 13, 1945 FOREIGNPATENTS Number Country Date 515,470 Great Britain Dec. 6, 1939

1. A CASTING CORE MATERIAL COMPRISING A MIXTURE OF SAND, A DRYING OIL, AND DEGERMINATED, PELLETED, PUFFED AND PULVERIZED CORN FLOUR. 